Rather than thinking in terms of right and wrong, let's consider this question in terms of 'spiritually good for you' vs 'spiritually bad for you.' Does watching a sporting event add anything to you spiritually? Does it help you to become a better Christian? Does it inspire you to pray more or read the Bible? In most cases, it takes your mind away from Jesus and away from spiritual things.
Most activities of this sort will not cause great damage when done in moderation, but when done consistently over time, they can cause great spiritual weakening and loss. We therefore suggest that people either avoid sporting events all together or keep them under strict limited control.